The present invention relates to a system, a server, a client, a method, and a program for sending messages by oblivious transfer.
A protocol called oblivious transfer is known (see, for example, Even, O. Goldreich, and A. Lempel, “A Randomized Protocol for Signing Contracts”, Communications of the ACM, Volume 28, Issue 6, pg. 637-647, 1985). The oblivious transfer is a protocol configured to allow a sender apparatus to send a receiver apparatus a message of an index designated by the receiver apparatus among N messages (X1, . . . , XN) held by the sender apparatus, but not to allow the sender apparatus to identify the designated index nor to allow the receiver apparatus to acquire any message of an index other than the designated index.